Sensors

Sensors are an exciting method of automatically generating input which can be used to trigger events based on movement, sound and light etc. The Raspberry Pi can be connected to many different types of sensor.

In this project we use a simple, passive infra-red sensor to detect movement. It operates by sending a current to the Pi when triggered.

Another type of sensor that could be used is an ultrasonic sensor, which sends a pulse of ultrasonic sound to determine the distance of an object from the sensor. This is a great sensor but it requires a little mathematics in order for it to work. Both the PIR and ultrasonic sensor can be picked up for less than £3 on eBay. The Pi can only directly use digital sensors as the GPIO doesn’t support analogue sensors, but for under £10 you can pick up an analogue to digital converter (ADC) which will bridge the gap.